| Differences between revisions 9 and 10 | Back to page |
|
Size: 879
Comment:
|
Size: 879
Comment:
|
| Deletions are marked like this. | Additions are marked like this. |
| Line 19: | Line 19: |
| Ans. What do you mean by contact? Does exchanging photons/gravitons count as contact? On a more practical level, it is ''very'' helpful to remember, "no contact, no force except gravity, in ''most'' problems of classical mechanics." | Ans. What do you mean by contact? Does exchanging photons/gravitons count as contact? On a more practical level, it is ''very'' helpful to remember, "no contact, no force except gravity," in ''most'' problems of classical mechanics. |
Which force?
Friction, air resistance, tension, spring force, normal force, etc. are all due to
- Gravitational force
- Electromagnetic force
- Strong force
- Weak force
Ans. A
The force is everywhere
When two objects exchange forces, they can do so without having to contact each other.
- Yes
- No
Ans. What do you mean by contact? Does exchanging photons/gravitons count as contact? On a more practical level, it is very helpful to remember, "no contact, no force except gravity," in most problems of classical mechanics.
The work energy “theorem”
The work energy theorem, $\Delta T = W$ where $T$ is the kinetic energy (and $\Delta T = T_2 - T_1$ is its change) and $W$ is the net work done on the particle, is
- always valid (in classical mechanics).
- valid only for conservative forces.